Wang Fang, Brunet Nicolas M, Grubich Justin R, Bienkiewicz Ewa A, Asbury Thomas M, Compton Lisa A, Mihajlović Goran, Miller Victor F, Chase P Bryant
Department of Biological Science, The Florida State University, Tallahassee, FL 32306-4295, USA.
J Biomed Biotechnol. 2011;2011:435271. doi: 10.1155/2011/435271. Epub 2011 Dec 1.
Familial hypertrophic cardiomyopathy (FHC) is a disease of cardiac sarcomeres. To identify molecular mechanisms underlying FHC pathology, functional and structural differences in three FHC-related mutations in recombinant α-Tm (V95A, D175N, and E180G) were characterized using both conventional and modified in vitro motility assays and circular dichroism spectroscopy. Mutant Tm's exhibited reduced α-helical structure and increased unordered structure. When thin filaments were fully occupied by regulatory proteins, little or no motion was detected at pCa 9, and maximum speed (pCa 5) was similar for all tropomyosins. Ca(2+)-responsiveness of filament sliding speed was increased either by increased pCa(50) (V95A), reduced cooperativity n (D175N), or both (E180G). When temperature was increased, thin filaments with E180G exhibited dysregulation at temperatures ~10°C lower, and much closer to body temperature, than WT. When HMM density was reduced, thin filaments with D175N required fewer motors to initiate sliding or achieve maximum sliding speed.
家族性肥厚型心肌病（FHC）是一种心肌肌节疾病。为了确定FHC病理背后的分子机制，使用传统和改良的体外运动分析以及圆二色光谱法，对重组α-原肌球蛋白（V95A、D175N和E180G）中三个与FHC相关的突变的功能和结构差异进行了表征。突变型原肌球蛋白表现出α-螺旋结构减少和无序结构增加。当细肌丝被调节蛋白完全占据时，在pCa 9时几乎检测不到运动，并且所有原肌球蛋白的最大速度（pCa 5）相似。细丝滑动速度的钙反应性通过增加pCa(50)（V95A）、降低协同性n（D175N）或两者兼而有之（E180G）而增加。当温度升高时，与野生型相比，含有E180G的细肌丝在低约10°C且更接近体温的温度下表现出调节异常。当HMM密度降低时，含有D175N的细肌丝启动滑动或达到最大滑动速度所需的马达更少。
